CATV networks use an infrastructure of interconnected coaxial cables, signal splitters and combiners, repeating amplifiers, filters, trunk lines, cable taps, drop lines and other signal-conducting devices to supply and distribute high frequency “downstream” signals from a main signal distribution facility, known as a “headend,” to the premises (e.g., homes and offices) of subscribers to the CATV services. The downstream signals transfer multimedia content to subscriber equipment, such as television sets, telephone sets, and computers. In addition, most CATV networks also transmit “upstream” signals from the subscriber equipment back to the headend of the CATV network. For example, the subscriber uses a set top box to select programs for display on the television set. As another example, two-way communication is essential when using a personal computer connected through the CATV infrastructure to the public Internet. As a further example, voice over Internet protocol (VoIP) telephone sets use the CATV infrastructure and the public Internet as the communication medium for transmitting two-way telephone conversations.
To permit simultaneous communication of upstream and downstream CATV signals and the interoperability of the subscriber equipment and the equipment associated with the CATV network infrastructure outside of subscriber premises, the downstream and upstream CATV signals are confined to two different frequency bands. The downstream frequency band is within the range of 54-1002 megahertz (MHz), and the upstream frequency band is within the range of 5-42 MHz, in most CATV networks. The entire CATV frequency band is therefore 5-1002 MHz.
The downstream signals are delivered from the CATV network infrastructure to the subscriber premises at a CATV entry adapter, which is also commonly referred to as an entry device, terminal adapter, or a drop amplifier. The CATV entry adapter is usually a multi-port device that provides a multiplicity of ports or connectors for connecting coaxial cables. A separate coaxial cable is connected to each of the ports and extends within the subscriber premises to the location of the subscriber equipment. Some homes have coaxial cables extending to cable outlets in almost every room, because of the many different types of subscriber equipment used in different rooms. For example, television sets are commonplace throughout the home. The multiple ports of the CATV entry adapter deliver downstream CATV at each cable outlet and conduct upstream CATV signals back through the premises coaxial cables to the CATV entry adapter, which delivers the upstream CATV signals to the CATV network.
In addition to television sets, computers, and telephones, a relatively large number of other entertainment and multimedia devices are available for use in homes. For example, a digital video recorder (DVR) is used to store broadcast programming, still photography and moving pictures in a memory medium so that the content can be replayed on a display or television set at a later time selected by the user. As another example, computer games are also played at displays or on television sets. Such computer games may be obtained or played over the Internet from the CATV network or from media played on play-back devices or game consoles connected to displays or television sets. As a further example, receivers which receive satellite-broadcast signals may be distributed for viewing or listening throughout the home. These types of devices, including the more-conventional television sets, telephone sets, and devices connected to the Internet by the CATV network, are generically referred to as multimedia devices.
The desire to use multimedia devices at multiple different locations within the home or subscriber premises has led to the creation of the Multimedia over Coax Alliance (MoCA). MoCA has developed specifications for products to create an in-home entertainment network for interconnecting presently-known and future multimedia devices. The MoCA in-home network uses the subscriber premise or in-home coaxial cable infrastructure originally established for distribution of CATV signals within the subscriber premises, principally because that cable infrastructure already exists in most homes and is capable of carrying much more information than is carried in the CATV frequency band. A MoCA network is established by connecting MoCA interface devices at the cable outlets in the rooms of the subscriber premises. The MoCA network is used to transmit multimedia content from one MoCA interface device to another.
The MoCA interface devices implement a MoCA communication protocol that encapsulates the multimedia content normally sent and received by the multimedia devices within MoCA packets and then communicates these MoCA packets between selected ones of the other MoCA interfaces devices connected at other cable outlets. The receiving MoCA interface device removes the encapsulated multimedia content, and delivers it to the connected computer, digital television or set-top box, or other multimedia device that then presents the multimedia content.
Each MoCA interface device is capable of communicating with every other MoCA interface device in the MoCA network to deliver the multimedia content throughout the home or subscriber premises. The entertainment or multimedia content that is available from one multimedia device can be displayed, played, or otherwise used at a different location within the home, without having to physically relocate the multimedia device from one location to another within the home. The in-home network communication of multimedia content is considered beneficial in more fully utilizing the multimedia devices present in modern homes. The MoCA+CATV interface devices also pass the upstream and downstream CATV signals between the CATV entry adapter and the subscriber devices.
Since the MoCA network may function simultaneously with the normal operation of the CATV services, the MoCA signals communicated between MoCA interface devices utilize a frequency range of 1125-1675 MHz, which is outside of the frequency band of CATV signals. This so-called D band of MoCA signals is divided into eight different frequency ranges, D1-D10, and these ten different D frequency ranges are used to assure communication between the selected MoCA interface devices. For example, the D1 band at 1125-1175 MHz may be used to communicate CATV television programming content between a MoCA interface device connected to a set-top box in a main room of the house and another MoCA interface device connected to a television set in bedroom of the house, while a MoCA interface device connected to a computer gaming multimedia device in a basement room of the house simultaneously communicates computer game content over the D6 band at 1375-1425 MHz to a computer located in a recreation room of the house. The MoCA frequency band also includes other frequency ranges outside of the CATV frequency band, but the D band is used to establish connections and communicate content between the MoCA interface devices.
If the high-frequency MoCA signals aren't blocked at the entry box, they may transmit information from the subscriber's premises or home to the headend that the subscriber does not wish to share. A PoE filter is often used to prevent (e.g., filter) the MoCA signals from being leaked outside the subscriber's premises or home and to reflect signals from port to port to ease the MoCA signal communication.
In conventional entry adapters, the PoE filter is positioned within the entry adapter, and all ports are required to allow MoCA and CATV transmission together. When more than five output ports are required from an entry device, the PoE filter alone cannot achieve the performance required. As a result, one or more diplexers may be used to implement a good MoCA path. Adding diplexers makes the design of the entry adapter very complicated, and repeatability of performance suffers from unit to unit. This often results in costly designs and the manufacturing of user-unfriendly products. The main reason to have all output ports meet the MoCA and CATV communication together is to prevent installation errors in the field. In the general installation practice, gateways and modems are set to transmit and receive CATV and MoCA signals. The other MoCA devices connected to the remainder of the output ports are set to communicate in the MoCA band only. Thus, having all ports meet MOCA and CATV specifications is not needed.
Because all output ports of an entry device need to have MoCA and CATV communication compatibility, the PoE and/or diplexers have to be integrated and tuned in the design to meet the required specifications. In the event that the CATV frequency band and/or the MoCA frequency band change in the future, the entire entry adapter may need to be replaced with a newer version that is compatible with the new frequency bands. What is needed is an improved entry adapter between the CATV network and the in-home network that distributes the CATV signal among multiple subscriber or multimedia devices within the subscriber's premises or home.